Optical brighteners of the benzoxazole series

ABSTRACT

Colorless or nearly colorless fluorescent benzoxazole compounds which correspond to the general formula   MAY BE USED AS OPTICAL BRIGHTENERS. In the above formula I, the radical R represents hydrogen, alkyl of one to four carbon atoms, cyclohexyl, halo lower alkyl, hydroxyethyl, lower alkoxy lower alkyl, di-(lower alkyl)-amino lower alkyl, tri-(lower alkyl)amonium lower alkyl, phenyl and phenyl lower alkyl, and R1 stands for hydrogen, lower alkyl or halogen, R2 stands for lower alkyl.

United States Patent Schinzel et al. July 4, 1972 [5 OPTICAL BRIGHTENERS OF THE References Cited BENZOXAZOLE SERIES UNlTED STATES PATENTS [72] Inventors: Erich Schinzel, Frankfurt am Main; Ulrich 3,262,929 7/1966 Okubo et a1. ..260/240 D Pintschovius, Kelkheim am Taunus; Karl Heinz Lebkucher, l-lofneim am Taunus, all Primary Randolph v f Germany Attorney-Curtis, Morris & Safford [73] Assignee: Farbwerlre Hoechst Aktiengesellschaft vor- [57] ABSTRACT mals Melster Lucius & Bruning, Frankf t/Mai fl Colorless or nearly colorless fluorescent benzoxazole compounds which correspond to the general formula [22] Filed: Sept. 15, 1970 [21] Appl. No.: 72,492

R; N Related U.S. Application Data [63] Continuation-in-part of Ser. No. 366,901,- May 21, R CH:CH

1964, abandoned, Continuation of Ser. No. 624,721, 0003 March 21, 1967, abandoned.

may be used as optical brighteners. In the above formula 1, the [52] U.S. Cl. ..260/240 D, 106/176, 117/335 T, radical R represents hydrogen, alkyl of one to four carbon 252/3012 252/186 260/75 260/78 atoms, cyclohexyl, halo lower alkyl, hydroxyethyl, lower al- 26O/88'7 260/479 R koxy lower alkyl, di-(lower alkyl)-amino lower alkyl, trilil liiifi'r zsza11111111111111:1:11:11???37253285283 alkyl, and R, stands for hydrogen, lower alkyl or halogen, R stands for lower alkyl.

3 Claims, No Drawings OPTICAL BRIGHTENERS OF THE IENZOXAZOLE SERIES tanol, tert. butanol, octanol, cyclohexanol, 2-, 3 or 4-methylcyclohexanol, 2-chloroethanol-(l), l-chloropropanol-(Z), glycol, propanediol-( 1,2), n-butane-diols-( 1,3) and (1,4), 2- methyl-n-butanediol-( l ,3), n-hexanediol-( 2,5 glycerin, penta-erythritol, diethylene glycol, triethylene glycol, glycol monomethyl ether, glycol monoethyl ether, glycol mono-nbutyl ether, 3-methoxy-n-butanol-( l glycide, phenol, mor p-cresols, xylenols, benzyl alcohol, 2-phenyl-ethanol-( 1), 4 isopropyl-benzyl alcohol, 2-dimethylamino-ethanol-( l 2- diethylamino-ethanol-(l), 2-di-n-butylamino-ethanol(1), 1

dimethylamino-propanol-( 2 The novel compounds are distinguished by an excellent fluorescence and very good fastness to light in brightening fibrous materials, above all those made from polyesters of the Now, we have found that colorless or nearly colorless type of polyethylene glycol terephthalate, polyamide, acetyfluorescent benzoxazole compounds which correspond to the lated cellulose and polyacrylonitrile. The optical brighteners general formula of the present invention can be used in known manner, either i in the form of solutions in water or in organic solvents or in the R, N form of dispersions, if desired with the aid of dispersants. The I amounts required, which may vary within wide limits, can be R CH==O H easily determined by preliminary tests. The compounds may 0 C 0 OR (I) also be used together with chemical bleaching agents, for example, oxidizing or reducing bleaching agents such as sodium chlorite, sodium boron hydride.

may be used as optical brighteners. 1n the above formula 1, the Funhermora, the novel compounds may also be added to radical R represems hydrogen alkyl of one to four carbon the commercial detergents for embellishing the goods to be atoms cyclohexyl hallo lower alkyl hyfjmxyethyl lower washed and good brightening effects are obtained on polyester koxy lower alkyl Zn-(lower alkyn'ammo lower alkyl fibers even when washing at temperatures below the boiling (lower alkyl)-ammonium lower alkyl, phenyl and phenyl point lower alkyl and stands for hydrogen lower alkyl or The instantly described 5,6-position disubstituted derivahalogen R2 Stands for lower alkyl and R1 and R2 taken tives as represented by structural formula 1 given above have together represent (CH2)3 or unexpectedly significantly superior properties as brighteners The benzoxazoles of the formula. 1 used m accordance with than the corresponding 5,7-position di-substituted derivatives the present invention as optical brighteners may be prepared as described in U 3 262 929 by various methods, for example, by the reaction of sub- Further, the glove] compundg may also be added to stituted oammoPhenols with the acid chlondcs 9 or spinning or molding masses which serve for the preparation of carbalkoxy-cinnamic acids and subsequent heating of the N- synthetic fibers filaments, foils or other Structures acyl'compoinds f an q q l of an gas i The following Examples illustrate the versatile possibilities solvents having a high boiling point, if desired or required, in 40 of application of these compounds but they are not intended the presence of catalysts such as zinc-chloride, whereby the tolimit them thereto. oxazole ring is closed under separation of water. Further, the interchange of ester radicals of 2-(carbomethoxy-styryl)- EXA 1 'benzoxazoles with higher boiling alcohols in the presence of the alcoholates of the respective alcohols is also possible. A fabnc l from polyethylen? tel'ephfhalate Furthermore, 2 (yan 5tyry1) bcnzoxazoks can be convened fibers, bleached in the usual manner with sodium chlorite and i 2-(carbo a]koxy S[y|-y]) benzoxazo1es with the aid f still having a slight yellow tint, was treated for half an hour at cohols and hydrogen chloride. Furthermore, the reaction of C wlth an aqueous bath comammg P htel' of the acid chlorides of 2-(carboxy-styryl)-benzoxazoles with compound (11) compounds which contain an alcoholic or phenolic hydroxyl group also leads to compounds of the general formula 1. 11,0

As o-aminophenols, there may be mentioned, for example, 4-amino-3-hydroxy-toluene, 5-amino-4-hydroxy-l ,2-xylene, H3O CII=( H -COOCH3 5,6,7,8-tetrahydro-3-amino-2-naphthol, 5-amino-6-hydroxyv 0 hydrindene or 6-chloro-4-amino-3-hydroxy-toluene. 5 5

As alcoholic or phenolic compounds which may be used for in dispersed form. After the treatment, the fabric showed an esterfying the 2-(carboxy-styry1)-benzoxazoles, there may be excellent white, which was not affected to a remarkable mentioned, for example, monoor polyhydric, aliphatic, degree upon exposure for lOO hours to the light of a Xenone cycloaliphatic, araliphatic alcohols, phenols, and the like, high pressure lamp. Instead of the compound (ll), there can such as methanol, ethanol, npropanol, isopropanol, n-bualso be used the compounds listed in the following table.

TABLE Constitution Melting point, C.

219-220 01 -N m 10H: =CH COOCH,

-167 H O N H C- LOH: =CHCOOCH:CIL

mas-150.5 H C N HaC OJ-CH= =CHCOO-CH2OH2CHI -in dispersed form and 0.5 g/l ofsodium chlorite The above listed compounds are also stable in a chlorite bleaching bath and give good brightening effects.

The 2-(4'-carbomethoxy-styryl)-5,6-dimethyl-benzoxazole II) mentioned above can be prepared as follows:

A 50 C warm solution of 22.5 parts by weight of 4-carbomethoxy-cinnamic acid-chloride in 100 parts by volume of chlorobenzene is slowly added, while stirring, to a 60 C warm mixture of 13.7 parts by weight of 5-amino-4-hydroxy-l,2- dimethyl benzene, 18 parts by weight of N,N-dimethyl-aniline and 100 parts by volume of chlorobenzene and the whole is further stirred for 2 hours at 60 to 65 C. After cooling, the reaction product which precipitates at 5 C is filtered 011' with suction and treated with steam until all adhering chlorobenzene and dimethylaniline is volatilized. After suction-filtration and drying, there are obtained 28 parts by weight of the 4-carbomethoxy-cinnamic acid amide of 5- amino-4-hydroxy-1,2-dimethyl-benzene having a melting point of 23 l 232 C (with decomposition).

In order to convert the compound into the benzoxazole derivative, the dried carboxylic acid amide (28 parts by weight) is heated in a flask provided with a gas inlet and a descending reflux condenser, while passing through nitrogen, together with 50 parts by volume of distilled trichloro-benzene and in the presence of 0.2 part by weight of molten zinc chloride, for 1 hour to 210 C on an oil bath. The molten mass, which crystallizes upon cooling, is combined at 60 C with 50 parts by volume of ethanol, the mixture is cooled to 5 C and filtered off with suction. There are obtained 25 parts by weight of 2-(4'-carbomethoxy-styryl)-5,6-dimethyl-benzoxazole which is purified by recrystallization from dioxane with the addition of animal charcoal. Melting point: 200 201 C.

Compound (11) can also be prepared by the following method:

Hydrogen chloride gas is introduced during 5 hours into a suspension of 10.0 parts by weight of 2-(4'-cyano-styryl)-5,6- dimethyl-benzoxazole (melting point 198 200 C) in 100 pans by volume of methanol. Upon cooling of the reaction mixture, 8 parts by weight of 2-(4'-carbomethoxy-styryl)-5,6- dimethyl-benzoxazole separate, which, after redissolution, has a melting point of 199 200 C and which is identical with the 2-(4-carbomethoxy-styryl)-5,6-dimethyl-benzoxazole prepared in the manner described above.

The preparation of the compounds listed in the table likewise does not represent difficulties. For example, the mentioned 2-(4'-carbobutoxy-styryl)-5,6-dimethyl-benzoxazole can be prepared as follows:

20 parts by weight of the above-mentioned 2-[4'-carbomethoxy-styryl1-5,6-dimethyl-benzoxazole are boiled under reflux for 6 hours in 500 parts by volume of n-butanol in the presence of 10 parts of sodium butylate. Upon cooling, 13 parts by weight of 2-[4'-carbo-n-butoxy-styryl]-5,6-dirnethylbenzoxazole crystallize out. After recrystallization from cyclohexane or ethyl acetate, there are obtained needles having a melting point of l 18.5 121 C.

EXAMPLE2 An unbleached fabric made from polyethylene glycol terephthalate filaments was bleached at a goods-to-liquor ratio of 1:20 for half an hour at 80 85 C and further bleached for half an hour at 98 C.

The bleaching bath, which had a pH-value of 3.5, contained P liter 159 91 i1!!8 sm wsqd l) (100 strength). The white of the fabric thus treated was bright and clear.

(III) 7 EXAMPLE 3 A fabric made from polyethylene glycol terephthalate filaments bleached in the usual manner was impregnated with an aqueous dispersion containing per liter 5 g of compound II and squeezed on the foulard to the extent that the fabric retained 60 percent of its weight of dispersion. The fabric was then treated for 60 seconds at 190 C with hot air. After this treatment it showed a beautiful uniform white.

EXAMPLE 4 0.5 percent of the compound (IV) was added to a detergent having the following composition:

12 of alkylaryl sulfonate 6 of oleylaminooctaglycol ether 4 of potassium pyrophosphate 8 of sodium salt of p-toluenesulfonic acid.

A greyed polyester fabric was washed for 10 minutes at C with a bath containing per liter 3 g of the above detergent. After this treatment, the fabric showed a beautiful agreeable white. Even after 10 washers of the above manner, no undesired discoloration could be observed.

The 2-(4'-carbethoxy-styryl)-5,6-dimethyl-benzoxazole (IV) can be prepared as follows:

A solution of 2.3 parts by weight of sodium metal in 50 parts by volume of ethanol is added at room temperature and while stirring to a suspension of 31.2 parts by weight of the acid chloride of 2-(4'-carboxy-styryl)-5,6-dimethyl-benzoxazole (light yellow crystals from toluene, melting point: 223 224 C) in 150 parts by volume of anhydrous dioxane. The whole is heated for 4 hours to 50 C and the ethyl ester that has formed is precipitated by means of water;

There are obtained 29.2 parts by weight of compound IV. After 4 recrystallizations from ethyl acetate using animal charcoal, the melting point is at l65- 167 C.

EXAMPLE 5 An unbleached fabric made from a copolymer consisting of at least percent of polyacrylonitrile was bleached for 30 minutes at 80 85 C, at a pH-value of 3.5, with a bath containing 1.2 of sodium chlorite strength) 1.0 of bleaching auxiliary (consisting of 32 of oleic acid methyl tauride, 60 of ammonium sulfate and 8 of sodium pyrophosphate),

0.2 ml/l of acetic acid 100 strength), and

1.2 ml/] ofsulfuric acid (1:10),

and then further treated for half an hour at 98 C. The bleaching bath contained 0.2 percent (addition in the form of an aqueous dispersion) of compound (V) i I cHl-cm H. CH=CH coo-om-cm-n CHz-CH;

U N (Melting point 132-131 C.) H

The quaternary ammonium salt of the general formula (VIII) can p e a edi sf wsit. t A mixture of 8 parts by'weight of compound (VI), 40 parts by volume of methanol and 2.8 parts by volume of dimethyl v sulfate is boiled for 1 hour under reflux. After suction-filtra- I) tion in the cold, 10 parts by weight of the quaternary ammonium salt having a melting point of 243 245245 C are obtained.

fOl'1I(')h"eSafore-mentioned compound (VI) can be prepared as 10 EXAMPLE 7 13 parts by volume of 2-dimethylamino-ethanol are added, A fabric consisting of 50 percent of vinylidene cyanide and while stirring, to a 70 (3 hot solution of the acid chloride of 50 p r f nyl acetate. l h in the usual manner, was 32.5 parts by weight of 2-(4'-carboxy-styrol)-5,6-dimeth ltreated for 30 minutes at 98 C, at a goods-to-liquor ratio of benzoxazole in 330 parts by volume of chlorobenzene. After 2 1520 with a bath Consisting of hours heating on the water bath, the product is filtered ofi 15 log/10f Phthalic acid dimelhylester with suction, treated at 50 C with a solution of 15 parts by 2 8 ofthe Sulfate y 'y 'p y y ether, and weight of potassium hydrogen carbonate in 200 parts by 8" ofcompound The determination of the white, carried out on a ZeisseElrepho at a wave length of 460 t, gave a value of 91.0 percent referred to magnesium oxide as standard with 100 percent. (The non brightened fabric showed a value of 83 percent).

What is claimed is:

l. A compound of the formula volume of water and washed with water. After drying, there are obtained 27 parts by weight of B-dimethylamino-ethyl ester of the general formula (VI). After recrystallization, the compound melts at 138 139 C.

EXAMPLE 6 N A fabric made from a copolymer containing at least 85 of 11,0 polyacrylonitrile, bleached in the usual manner, was treated at -cH=c Q 0 R a goods-to-liquor ratio of 1:20 with 0.06 g/l of an aqueous HzC solution of compound (VII) 0 I I M Mm an M I M H C- N CH3 H IIiC CH=CH COO-CH:CH:NCH; O-SO CH;

\O/ CH (VII) (Melting point 271274 C.)

for half an hour at 98 C. After the treatment, the fabric in which R is a, B-ethoxyethyl 0r B-( n'm yl ammonium)- showed a brillant white which could not be obtained without 40 ethyl methos lfa e groupusing an optical brightener. 2. A compound according to claim 1 wherein R is In similar manner, there may also be used the following CH Cl-I OCH CH I benzoxazole of the general formula (VIII) instead of com- -A mP n a r lng to l im lwhef mRls pound (VII): oHi0miflonoqEi-sm-omn 111C N CH:

Inc J-cnamQ-ooo-om-cmax-0H, 0-s0,0cH,

on, (VIII) UNITED STATES PATENT orrIcE I CERTIFICATE OF CQRRECTION Patent No. z 671 281 Dated Julv 1972 Invent0 Schinzel et a1.

Itis certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below;

In the Heading:

7 Under Related U.S. ApplicationData and after "Ser. No. 566,901," correct May 21, v 196%" to read --May 12,- 19 6%"; i

After March 21, 1967, abandoned." and before [52] U.s.' c1." insert --Foreign Application Priority Data May 17, 1963 Germany; F 39 765".

Signed and sealed this 5th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents USCOMM-DC 60376-P69 U.S GOVERNMENT PRINTING OFFICE: 1969 0-366334 FORM PO-105O (10-69) 

2. A compound according to claim 1 wherein R is -CH2CH2-OCH2CH3.
 3. A compound according to claim 1 wherein R is 